1. Field of the Invention
The present invention relates to a paper feeding apparatus in an image forming apparatus, such as a copying machine, a printer, or the like, and particularly relates to an apparatus in which a plurality of sheets of paper are simultaneously moved in a paper feed path with less waiting time.
2. Description of the Prior Art
In an image forming apparatus, such as an electronic copying machine using a xerography system, a laser printer, and so on, a toner image is formed on an image carrying body, such as a photosensitive drum. The toner image is next transferred onto paper, and the paper is passed through a means to fix the toner image on the paper. Automatic double-side copying can also be performed by transferring one image onto a back surface of paper after another image has been copied on a front surface of the paper.
In such an automatic double-side copying machine, after transferring a toner image to the surface of paper and fixing the image, the paper is stored in an intermediate tray, and then, the paper is extracted from the intermediate tray and fed to the image transfer portion to copy on the back side of the paper.
Also, in an apparatus such as a laser printer or the like, many different sizes of paper are stored in several paper trays so that paper having a desired size, or having a size corresponding to the size of the original, may be fed out from the paper trays.
In such an apparatus, a control means is generally used so that when a toner image is formed on an image carrying body, paper is fed out from a paper tray in proper timing with the image carrying body.
However, in a large-sized machine, the paper feed path from the paper tray to the image carrying body is comparatively long. There is a problem in that the copy output is slow if paper is fed from the paper tray in synchronization with the image formation on the image carrying body.
Therefore, it is desirable to feed paper not in synchronization with the image formation, but earlier, so that the paper is temporarily stopped in an upstream portion of the feed path in a standby position. The paper is fed to an image transfer position from the standby position in synchronization with the image carrying body.
However, conventional stopping means pushes the front end portion of the paper into a gate member so that the paper is stopped with a curved or buckled surface. Accordingly, a problem arises if the paper remains curved for a long period of time, because the paper tends to retain the curved shape. Trouble may occur in the subsequent feeding of such curved paper.
In an image forming apparatus, such as an automatic double-side copying machine or the like, an intermediate tray to temporarily store paper copied on one side is often used. In order to feed paper copied on one-side to an image transfer portion in such an automatic double-side copying machine, the paper feed path is often longer than the distance between the paper tray and an image transfer portion in an ordinary machine.
Therefore, conventional automatic double-side copying machines require a long time period to prepare a copy. Since a long time period from pushing the start button switch until a copy reaches an output tray is required, the number of copies per unit time is small.